In D.C., if a new car does not conform to all warranties for the first 18,000 miles or two years (whichever comes first), the dealer is obligated to correct the defect at no charge, after being given written notice.
If the defect is uncorrectable after a “reasonable number of attempts,” the dealer must give the consumer a refund if the defect substantially impairs the use and market value of the car.
A “reasonable number of attempts” means (a) four or more attempts to fix a non-safety feature over two years, (b) one or more failed attempts to fix a safety feature, or (c) that the car has been out of service for more than 30 days during the time of ownership.
Source: D.C. Lemon Law Statute